Electric space heater and method of manufacture



J. E. GOF F ELECTRIC SPACE HEATER AND METHOD OF MANUFACTURE July 5,1960

Filed Dec. 23, 1957' United States 1 ELECTRIC SPACE HEATER AND METHOD OFMANUFACTURE James E. Golf, Knoxville, Tenn., assignor to ElectricHeaters, Inc., Knoxville, Tenn., a corporation of Ten- ,nessee FiledDec. 23, 1957, Ser. No..704,824

1 Claim. (Cl. 219-34) This invention relates broadly to the electricspace heater art and in its more specific aspects it relates to a noveltype of electric resistance unit embodying heat conduction anddissipation characteristics and the method of manufacturing such unit;and the nature and objects of the invention will be readily recognizedand understood by those skilled in the arts to which it relates in arecertain unsatisfactory features which are inherent in the types nowbeing produced. These unsatisfactory features are particularly apparentin connection with baseboard heaters where space is limited and size ofcomponents is a prime consideration. In baseboard and the like heaterswhich conventionally are the sole heating means for an area, heatingefliciency is essential. It is also highly desirable that baseboardheaters be endowed with long lasting characteristics, not solely forreasons of economy but also because of the difiiculties which may beencountered in dismantling the heater for servicing.

Sheathed tubular resistance elements are mass produced and are ofrelatively low cost and for these reasons would appear to be useful asthe heating element in baseboard and the like heaters. However, I havefound that these elements alone do not provide suflicient heat becausethe sheathed tubular resistance elements, per se, lack sufiicientconductive surface area for proper heat dissipation into the space to beheated.

Heaters are produced which use elements which are fabricated bythreading coiled resistance wire inside of porcelain spacers. Suchelements are expensive, short lived and are no more eflicient in heatingan area than are the aforementioned sheathed tubular resistanceelements.

In considering the problem of heating efiiciency and economy it must beappreciated that there is insufficient space to utilize a plurality ofrows or lengths of resistances in a baseboard heater, nor is itpractical to provide a heat reflecting member as is often provided inportable electric space heaters.

In my efforts to use the mass produced low cost metallic sheathedtubular resistance elements in baseboard and the like heaters and stillprovide an efficient heat producing arrangement I combined the sheathedtubular resistance element with a metallic heat conductive surface providing the necessary heat dissipating area. However, I discovered thatmerely using resistance unit and fixing it to and combining it with ametallic heat conductive surface was not enough and was unsatisfactoryfor use as the heat producing medium in a baseboard or the like spaceheater. In use of a metallic sheathed tubular amass Patented July 5,1960 the aforementioned combination there was noise due to expansion ofthe metals under the temperature rise causing a slippage of the sheathedtubular resistance element relative to the metallic heat conductivesurface. In order to provide a practical device a channel was formed inthe heat conductive surface and the sheathed tubular by unequalexpansion of the heat conductive surface a large.

relative to the metallic sheath housing the resistance element and itsinsulation.

' All noise and undue wear have been eliminated by forming the heatconductive member and the metallic sheath of the element out of metalshaving the same coefficients of expansions. In this manner the rates ofexpansion are the same, undue stresses and strains are eliminated and aquiet and eflicient heater results.

Unusually satisfactory results have been experienced by forming the heatconductive member or fin of a aluminum and also providing an aluminumsheath for the'tubular resistance element. In this manner both of themembers will expand at similar rates, there will be no slippage betweenthem and all noises will be eliminated. While I do not intend to limitmy unit to one made of aluminum it may be noted that the heatconductivity of aluminum is approximately three times that of, forexample, tin, nickel and iron.

I have not only evolved the broad concept generally outlined abovebut Ihave also structurally embodied the concept into a practical, eflicientheater which may be easily and economically produced. In accomplishingmy aims I have used an extruded aluminum shape for the heat conductiveand dissipating member and not onlyhave I formed the shape in a mannerto cause proper heat dissipation but I also provide it with meansreceiving the resistance element in heat transfer relation thereto andthe means is manipulable in a facile manner to permanently afiix theelement to the member.

In using an extended aluminum shape I am enabled to vary the shaping ofthe heat conductive member for different installations, and it Will beapparent that this adds to the versatility of my proposal.

A simple and economical method of effecting this combination of thetubular resistance element with the heat conductive member has beendevised which presages rapid and economical production of the units.

This combination comprising the sheathed tubular resistance element andthe heat conductive member forms a unitary structure which provides forsubstantial heat dissipation while requiring relatively little space andthe unit is particularly adapted for use in baseboard heaters wherespace allotments for various components are not While I shall describethe unit as used in abuseboard heater, it is to be understood that itand the underlying principlesinvolved are adaptable for usein a varietyof types of electric space heaters.

My invention is also concerned with the heater assembly involving aunique mounting and arrangement of parts wherein heat convectioncurrents are generated which add to the efiiciency of the space heater.

The unitary resistance element and the parts of the heater assembly maybe mass produced at low cost.

The heater is of pleasing appearance because of its compactness which ismade possible by using the unitary 3 structure involving the heatconductive member and the tubular resistance element.

With the foregoing general objects, features and results in view, aswell as certain others which will be apparent from the followingexplanation, the invention consists in certain novel features in design,construction, mounting and combination of elements, as Will be morefully and particularly referred to and specified hereinafter.

Referring to the accompanying drawings:

Fig. 1 is a perspective view illustrating a baseboard heater includingthe unitary structure of the heat conductive member and the tubularresistance element.

Fig. 2 is an end View in section of the extruded heat conductive memberand illustrating a sheathed tubular resistance element in position to bedisposed in the channel formed in the member.

Fig. 3 is an end view in section of the completed unitary structure ofthe heat conductive member and the sheathed tubular resistance element,with parts of the member broken away.

In the accompanying drawings, and particularly Figs. 2 and 3 thereof, 1have used the numeral 1 to designate in its entirety the heat conductivemember and the numeral 3 to designate in its entirety the sheathedtubular resistance element.

The heat conductive member comprises an extruded.

shape preferably of aluminum, provided with an upper fin 5 and a lowerfin 7. The upper and lower fins are connected by an intermediate curvedrib or core section 9 from the upper and lower sides of which flanges 11project forwardly forming a channel or recess 13. If desired the lowerfin 7 may be formed at its end with a section 15 extending forwardly atan angle with respect to the major portion of the fin.

The heat conductive member 1 is provided the fabricator of the unit inextruded lengths in the shape and form illustrated in Fig. 2 and thefabricator may cut the lengths to provide the members in any desiredindividual length. It will be appreciated that the shaping dimensionsetc. of the fins may be varied to suit the requirements of specificinstallations without departing from the spirit and scope of myinvention.

The sheathed tubular resistance element 3 provides the resistance Wire17 encased within a circular body of any suitable insulation 19 whichmay be magnesium oxide and the insulated resistance wire is encasedwithin a metallic sheath 21.

As explained above the heat conductive member 1 and the sheath 21 of thetubular resistance element 3 are formed of metals, preferably aluminum,having the same coelficients of expansion so that the rates of expansionand contraction will be the same under thermal variations.

When it is desired to fabricate a unitary structure comprising the heatconductive member and the sheathed tubular resistance element, a lengthof the heat conductive member is cut from the shape which has beensupplied to the fabricator in the shape shown in Fig. 2 and a sheathedtubular resistance element 3 cut to a length substantially the same asthat of member 1 is inserted in channel 13 which is formed by curvedportion 9 and flanges 11. It will be understood that the curved portion9 of member 1 is dimensionally such that the element 3 will be snuglyreceived therein. When the tubular element is inserted in the channel asdescribed above the flanges 11 are rolled about the element 3 into theposition 12 illustrated in Fig. 3. This action of rolling flanges 11about the element binds the element in the slot or channel of the heatconductive member providing a sturdy unitary structure endowed with theattributes necessary to a heating and heat dissipating unit. It will berecognized, of course, that the wire 17 is connected to an electricpower source in any suitable and conventional manner.

It will be noted that the fins 5 and 7 of the heat conductive memberextend from the center section in different planes which are on oppositesides of the heating element 3. Due to this construction the air flowingin channels D and B will sweep across at least one surface of both fins.

Since the metal of the heat conductive member 1 and its parts are formedof a metal having the same coeflicient of expansion as the metal of thesheath 21 these two parts will have the same rate of expansion andbinding and resulting noises will be eliminated.

In Fig. l of the drawings I have illustrated one arrangement whereby theunit composed of member 1 and element 3 may be satisfactorilyincorporated in a baseboard or other generally similar type of spaceheater.

The assembly may include a mounting member designated generally by thenumeral 23, this member is fabricated to provide a base 25 having anupturned lip 27 along the front edge thereof. From the rear edge of thebase a body or backing member 29 extends and at its top edge a forwardextending top flange 31 is provided having a downturned lip 33 along itsforward edge.

I may provide an inclined plate 35 which is fixed to upturned lip 27 inany suitable manner and extends upwardly and rearwardly therefrom forfixing in any suitable manner to backing member 29 as at 37.

The assembly includes a battle member 39 provided at its top edge with aforwardly and upwardly extending bafile flange 41 and at its lower edgewith a forwardly and downwardly extending bafiie flange 43, the bafiie39 being spaced from mounting member 29 providing an air or convectionduct A therebetween, the flange bafiie 41 being spaced from flange 31and lip 33 providing an air or convection duct B therebetween and theflange baffle 43 being spaced from plate 35 providing an air orconvection duct C therebetween. The ducts A, B and C are incommunication with each other.

I provide a forward baflie 45 which is spaced from baiile 39 and itsbafiie flanges, and I position the heating unit composed of heatconvective member 1 and retsistance element 3 between baffles 39 and 45providing air or convection ducts D and E between these parts of theassembly. Grooved elements 47 may be provided on the outer face ofbaffle 45, one adjacent the top edge thereof and the other adjacent thebottom edge thereof. I provide a cover plate 49 having lips 51 formedalong its top and bottom edges adapted to hook into the grooved elements47 to support the cover plate in position. The cover plate is outwardlybulged to space it from forward baffle 45 forming an air space F betweenthese two components of the assembly. Screws 53 or any other suitablemeans may extend through the assembly in order to maintain the partsthereof in the described relative positions.

It will now be appreciated that the major convection currents D and Ecause air to flow over and in contact with the heating units, includingthe fins which extend substantial distances through the currents D andE. It will be further appreciated that A, B and C also carry air warmedby baffle 39. At the top of all the ducts the currents of heated air aredirected forwardly away from the wall which assures clean operation ofthe heater. The cover plate 49 may be touched and will not be hot enoughto burn because of the air pocket F therebehind.

I It will now be evident that I have devised an efficient' and easilyproduced heater element and a space heater incorporating the heaterelement which is of compact proportions and is endowed with excellentheat producing qualities.

I claim: Y

An electric space heater including, in combination, a mounting member,spaced apart elongated front and rear bafflles supported from saidmounting member providing an air flow channel therebetween, an elongatedmetallic heat conductive and heat dissipating member supported from saidmounting member in said channel in spaced relation with respect to saidfront and rear bafliles, said heat conductive and heat dissipatingmember comprising an upper heat conductive and dissipating fin and alower heat conductive and dissipating fin, -a section being providedbetween and connecting said fins and having a longitudinally extendinggroove formed therein, a tubular heating element including a resistanceelement encased within a metallic sheath and positioned within saidgroove in substantially continuous thermal engagement with the wallthereof, a continuous flange formed on each side of said groove integralwith said section and rolled over said tubular heating element and insubstantially continuous thermal engagement therewith for transfer ofheat from the former to the latter and to the heat conductive and heatdissipating member, and the metals from which said heat conductive andheat dissipating member and said metallic sheath are formed havesubstantially the same coefiicients of expansion, and the entire lowerfin extending in a plane on one side of the axial plane of said tubularheating element and the entire upper fin extending in a plane on theother side of the axial plane of said tubular heating element, wherebythe air flowing through said channel is heated by said heat conductiveand heat dissipating member and said tubular heating element, and saidsection provides minimum restriction to flow of air over said heatconductive and heat dissipating member.

References Cited in the file of this patent UNITED STATES PATENTS1,664,171 Hicks Mar. 27, 1928 1,848,716 Hart et al. Mar. 8, 19322,019,913 Kotrbaty Nov. 5, 1935 2,153,267 Morse Apr. 4, 1939 2,277,921McCullough et a1 Mar. 31, 1942 2,281,299 Steenstrup Apr. 28, 19422,347,957 McCullough May 2, 1944 2,578,136 Huet Dec. 11, 1951 2,799,763Hicks July 16, 1957 FOREIGN PATENTS 264,296 Great Britain Jan. 20, 192739,314 France July 28, 1931 (Addition to French Patent No. 695,636)655,692 Great Britain Aug. 1, 1951 720,939 Great Britain Dec. 29, 1954

